Work holder for heat-treating apparatus



June 30, 1942. H. E. soMEs WORK HOLDER FOR HEAT TREATING APPARATUS original Filed June s, 1939 INVENTOR Howard E. Somes A TTORNE Y Palettes June 3o, 1942 WORK HOLDER Foa HEAT-TREATING APrAaA'rUs Howard E. Somes, Detroit, Mich., a'ssignor to Budd Induction Heating, Inc., Philadelphia, Pa., a corporation of Michigan Original application June 8, 1939, Serial No.

277,996. Divided and this application September 22, 1941, Serial No. 411,852

14 claims. (Cl. 21e-1c) This application is a division of my copending application Serial No. 277,996, iiled June 8, 1939, for Progressive heat-treating apparatus and method, now Patent No. 2,281,333, dated April 28, 1942.

The present invention relates in general to induction heat treating and in particular to the differential heat treatment of the interior portions of hollow objects, an importantpurpose being the hardening or tempering of such portions of objects of a material hardenable by heat treatment, such as various ferrous alloys.

A primary object of the invention is the provision of an improved apparatus for heat treating relatively vlong hollow cylindrical objects, such as cylinder sleeves for internal combustion engines, in increments progressing continuously from end to end, and including an improved work holder for use in an induction heat-treating machine of the type shown and described in my copending application Serial No. 164,320, i'lled September 17, 1937, for Induction heattreating apparatus, now Patent No. 2,281,331, dated April 28, 1942.

A more specific object is the provision of an improved means for properly locating and holding the cylindrical workpiece relative to the heating head to insure proper axial alignment therewith, together with means in association therewith for avoiding abrupt change in the inductive reluctance of the heat-treating head during its movement into and out of the ends of the workpiece.

With the above and other objects in View, it will be apparent to those skilled in the art to which the invention appertains, the present invention consists in certain features of construction and combinations of parts to be hereinafter described with reference to 'the accompanying drawing and then claimed.

In the drawing which illustrates a suitable embodiment of the invention,

Figure 1 is a vertical axial section taken substantially on line I-I of Figure 2 and showing the work holder and workpiece in operating position with the heat-treating head in starting position, and

Figure 2 is a top plan view of the Work support, the heating head being removed therefrom.

Referring to the accompanying drawing in which like numerals refer to like parts, the induction heat-treating head I which forms the subject matter of my parent application Serial No. 277,996 aforesaid, embodies a core II of magnetic material carried by a mandrel I2 and having a surrounding inducing coil I3. The ends I4 of the core i l extend radially across the ends of the coil i3 as shown. Associated with and carried by the head l0 are cylindrical parts l5 and I6 which are axially spaced to provide a circumferential nozzle passage .I1 for quenching uid. The induction heating head I0 is described in detail in my application Serial No. 277,996 afore.. said, and need not be further described for the purpose of the present disclosure.

As set forth in said copending application, the heating head is arranged to be moved through the bore of the cylindrical workpiece 6| which, as shown for the purpose of illustration, is in the nature of an engine cylinder, to and through one end and then moved back through the bore during which return movement the bore is progressively heated and quenched to harden the same.

The work holder of the present invention for holding the workpiece Bl in proper position for heat treatment by the heat-treating head IU embodies a structure 62 arranged to be supported in any suitable manner such as on a rotary support 63 indicated in dotted outline, like that shown and described in my copending application Serial No. 164,320 aforesaid. The work holder structure comprises a pair of upper and lower annular holding elements 64 and 65, respectively, which are held in vertically spaced relation by columns 66 supported in the lower holding element 65. The spacing columns 66 are provided at their upper ends with dowel portions on which the upper holding element 64 is removably mounted, one of the dowel portions, such as 6l, being longer than the remainder, such as 68, so that the upper holding member 64 may be raised clear of the shorter dowel without complete removal from the holder structure to facilitate loading and unloading the holder, as will be hereinafter described. inasmuch as the upper and lower holding elements 64 and 65 are substantially the same in structure and function, a detailed description of one, for example the lower one, will sufiice.

Each holding element is provided with an end abutment ring 69 for engagement with the ends of the workpiece 6I, the upper and lower abutment rings 69 bearing against the opposite ends of the workpiece under the weight of the upper holding element 64 to hold the workpiece against axial displacement. Each ring element 69 in order to clamp the cylindrical workpiece 6| centrally of the holder against radial displacement is provided with a toroidal-shaped spiral spring than by direct radial compression of the convolutions.

Countersunk in each of the annular holding elements is a cylindrical extension element 12 built up of tapered radial laminations having one end portion arranged to overlap an end of the workpiece in close proximity thereto to form an axial extension of the workpiece in a generally axial direction, but flared outwardly away from the inner surface of the cylindrical workpiece a suflicient radial distance to enclose the heat-treating heat in positions beyond the ends of the workpiece.

In order to load the work holder with a cylindrical member 6I, the upper annular holding element 64 is raised above the short dowels 68 and swung about the longer dowels 61 as an axis to one side of the machine whereupon the workpiece may be set down upon the lower abutment u ring 69 with the lower end thereof embraced by the lateral clamping spring 10, after which the upper holding element 64 may be swung back over the workpiece into axial alignment therewith and set down upon the upper end of the workpiece over the shorter dowels 68 with the upper extension 12 bearing upon the upper end of the workpiece under` the weight of the element 64 with the upper toroidal spring 10 bearing radially against the upper sides of the workpiece.

With the parts thus proportioned and arranged, it will be seen that the heat-treating head may be moved through the workpiece from a position below the lower end of the workpiece surrounded by an end extension 12 of low permeability, .to and out of the upper end of the workpiece through the upper end extension 12 of low permeability. The end extensions 12 in eiect form axial continuations of the workpiece to lavoid and effects in the treatment of the worklow permeability tend to avoid abrupt change in the inductive reactance of the heat-treating head during its movement into and out of the ends of the workpiece. A function of the flared lform of the extension members 12 is to vary the reactance of the end extensions and thereby compensate for the dierence in permeability between the workpiece and such extension members. y

The coil springs 10 materially assist in holding the workpiece properly centered with ,respect to the end extensions 12.

In the use of the apparatus above-described for carrying out a preferred method of heat treatment, it being assumed that the arbor I2 and work` holder 62 are mounted for relative axial and rotary motion in any known or other suitable manner, which, for example, might be like that shown in the aforesaid copending application Serial No. 164,320, the arbor I2 is moved downwardly to pass the heat-treating head I0 through the workpiece 6I to a position ISI) just below the lower end of the workpiece where the heat-treating head will be surrounded by the lower low-reluctance end extension 12. In this position the inducing coil of the heat-treating head is energized from a suitable source of highfrequency current supplied to the coil by way of the arbor I2 in any suitable manner such as, for example, that shown in said application Serial No. 164,320.

The heat-treating head thus energized, and for the moment below and beyond the cylindrical workpiece 6|, is surrounded by the low reactance extension element 12 whereby its inductive reactance is maintained at a desirable degree. Immediately upon energization of the inducing coil, the heat-treating head is moved upwardly and out of the upper end of thev workpiece, preferably at a uniform rate of travel, the energizing current being cut off after the inducing coil passes upwardly out of operative relation with the workpiece 6I. Preferably, the energizing current is cut off before the inducing coil leaves the upper low-reluctance extension 12so as to prevent complete removal of the coil from the surrounding medium of low reluctance and thereby consequently prevent sudden reduction of the inductive reactance of the coil element. Thus heating currents are generated in the workpiece occupying a field in proximity to the heattreating head, which field of current occupancy and the resulting heated zone is progressed upwardly through the workpiece with the upward movement of the heat-treating head.

Also, upon energization of the inducing coil or slightly in advance thereof and while in the initial position shown in Figure 1, cooling and quenching lluid is forced through the hollow arbor I2 from any suitable source of supply, not shown. This cooling fluid passes through the head and outwardly through the nozzle passage I1. Immediately that the lower peripheral edge of the lower core extension reached the lower edge of the workpiece at which moment the lower end of the workpiece is about at its highest temperature, the sheet or jet of cooling issuing from the nozzle passage I6 contacts with the adjacent portion of the workpiece to immediately initiate the quenching of such portion. This quenching of the inner surface of the workpiece continues as the heat-treating head moves upwardly, and the progressive quenching operation is continued until and after the heat-treating head has passed beyond the upper end of the workpiece. It is to be understood that in the use of the invention herein-disclosed either the heat-treating element or the workpiece, or both, may be moved to effect the required relative movement between them, and that the mere mechanical inversion necessary to change from one form of relative movement to the other falls within the spirit of the invention and was intended to be covered by those of the appended claims specifying either of such forms of movement in accordance with the doctrine of equivalents.

While I have thus herein shown and described a specific embodiment and useful application of the present invention for the sake of disclosure, it is to be understood that the invention is not limited to such specific embodiment and mode of application, but contemplates all such variants and modications thereof as fall fairly within the scope of the appended claims.

What is claimed is:

l. In combination, an induction heat-treating head having an inducing coil of deiinite axial length arranged to be passed through a hollow cylindrical workpiece from outside of one end through and out of the other end, a holder for the workpiece, and a pair of annular end pieces of .low magnetic reluctance carried by the holder arranged to form short hollow cylindrical extensions for each end of the workpiece effectively extending each end a distance equal to at least the axial length of the said coil and having their inside surfaces outwardly flared.

2. In an induction heat-treating machine, a work holder for holding a hollow cylinder whose inner wall is to be heat treated, comprising a pair of annular holding elements space-d apart in axial alignment, a work abutment element for each holding element arranged to bear against an adjacent end portion of the cylinder in a direction axially of the cylinder, a spring element mounted on each holding element, each arranged to bear radially inwardly against the adjacent end of the cylinder, and a short cylindrical extension element of low magnetic reluctance mounted in each said holding element each arranged to form an extension of the adjacent end of the cylinder.

3. In combination an induction heat-treating head having an inducing coil of definite axial length arranged to be passed through a hollow cylindrical workpiece from outside of one endI through and out of the other end, a holder for the workpiece having upper and lower annular holding elements; means holding said holding elements spaced apart axially to hold a cylindrical workpiece between them in axial alignment therewith, an annular end abutment element for each holding element arranged to abut an adjacent end pol-tion of the workpiece to hold the latter'against axial movement, and a toroidal shaped spiral spring in each holding element arranged to bear radially inwardly against the outer wall of the cylindrical workpiece near the adjacent end thereof.

4. In combination an induction heat-treating head having an inducing coil of definite axial length arranged to be passed through a hollow cylindrical workpiece from outside of one end through and out of "the other end, a holder for the workpiece having upper and lower annular holding elements arranged in axial alignment to hold a cylindrical workpiece between them, an end abutment element for each holding element arranged to abut an adjacent end f the workpiece, a toroidal shaped spiral spring in each holding element arranged to bear radially inwardly`r against the outer wall of the cylindrical workpiece near the adjacent end, and a pair of annular end pieces of low magnetic reluctance, mounted one in each holding element and arranged to extend from the abutment element axially away from the workpiece and in axial ahgnment therewith to form a short extension of the workpiece of a length at least that of the axial length of the inducing coil and having an inside conical surface ilared away from the workpiece from a diameter at the end adjacent the workpiece substantially equal to that of the inside diameter of the workpiece.

5. In combination, an induction heat-treating head having an inducing coil of denite axial length arranged to be positioned within the hollow of a cylindrical workpiece to be heat treated, a holder for holding the workpiece in predetermined position relative to the heating head, embodying a pair of spaced annular holding elements, and a pair of ,toroidal-shaped' spiral springs, one being carried by each of said holding elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall of the workpiece near the ends thereof.

6. In combination, an induction heat-treating head having an inducing coil of definite axial length arranged to be positioned within the hollow of a cylindrical workpiece to be heat treated, a holder for holding the workpiece in predetermined position relativeV to the heating head, embodying a pair of spaced annular holding elements, andv a pair of toroidal-shaped spiral springs, one being carried by each'of said holding elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall of the workpiece near the ends thereof, the convolutions of each of said springs being angularly biased relative to the radius of the spring toroid.

7. In combination, an induction heat-treating head having an inducing coil of definite axial length arranged to'be positioned within the hollow of a cylindrical workpiece to be heat treated, a holder for holding the workpiece in predetermined position relative to theheating head, embodying a pair of spaced annular holding elements, and a pair of toroidal-shaped spiral springs, one being carried by each of said holding elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall Yof the vworkpiece near the ends thereof, each of said holding elements having an annular groove therein surrounding the spring supported thereby.

8. In combination, an ,induction heat-treating head having an inducing coil of denite axial length arranged to' be positioned within the hollow of a cylindrical work-piece to be heat treated, a holder for holding the workpiece in predetermined position relative to the heating head, embodying a pair of spaced annular holding elements, said holding elements carrying annular means for abutting the ends of the workpiece, and a pair of toroidal-shaped spiral springs, one being carried by each of said supporting elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall of the workpiece adjacent said abutments.

9. In combination, an induction heat-treating head having an inducing coil of deiinite axial length arranged to be positioned within the hollow of a cylindrical workpiece to be heat treated, a holder for holding the workpiece in predetermined position relative to the heating head, embodying a pair of spaced annular holding elements, a plurality of means for holding said holding elements in predetermined axially spaced relation, and a pair of toroidal-shaped spiral springs, one being carried by each of said holding elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall of the workpiece near the ends thereof.

10. In combination, an induction heat-treating head having an inducing coil of definite axial length arranged to be positioned within the hollow o1' a cylindrical workpiece to be heat treated, a holder for holding the workpiece in predetermined position relative to the heating head, embodying a pair of spaced annular holding elements, a plurality of means for holding said holding elements in predetermined axially spaced relation, anda pair of toroidal-shaped spiral y springs, one being carried by each of said holding elements, said springs being coaxially aligned and arranged to securely bear radially inwardly against the outer wall of the workpiece near the ends thereof, one of said holding elements being axially slidable with respect to all of said means but one for disengagement therefrom and being pivotally movable on said one for disposition out of alignment with said other holding element to permit loading and unloading of the lworkpiece.

11. In an apparatus for heat treating a workpiece of magnetic material by electro-magnetic induction having a heatinglcoil arranged for movement into and out of inductive relation with the workpiece, the combination with said coil of means arranged to be positioned adjacent one end of the workpiece to be heat treated to provide a magnetic circuit element for said coil when said coil is at least partially out oi inductive relation with the workpiece to minimize end leffects in the heat treatment; said circuit element bination with said coil of means arranged to be r positioned adjacent an end of the workpiece to be heat treated to provide an axial end extension thereof and to constitute a magnetic circuit element for said coil when said coil is at least partially out of induction relation with such workpiece end to minimize end effects in the heat treatment at such end, said means tapering in thickness longitudinally from such end in decreasing increments to compensate for diiferences in permeability between the workpiece and said means.

13. In an apparatus for heat treating the bore oi a hollow cylindrical workpiece of magnetic material by electro-magnetic induction having an induction heating coil arranged for 'movement into and out of inductive 'relation with the surface of .the workpiece bore, the combination with said coil of annular means of magnetic material arranged to be positioned at an end of the workpiece to provide an axial extension thereof and to constitute a magnetic circuit element for said coil when said coil is at least partially out of inductive relation with such workpiece end to minimize end effects in the heat treatment at such end, said annular means tapering in radial thickness from a maximum adjacent such end to a minimum axially remote therefrom to compensate for differences in permeability between .the workpiece and said annularmeans.

14. Apparatus for heat treating a hollow cylindrical object of magnetic material at and near the inner surface thereof comprising an electromagnetic induction heating element and having an internal magnetic core, and annular means of magnetic material arranged to be positioned at one end of the object to form with the object to be heat treated and said core, substantially the entire magnetic circuit of said heating element when said heating element is at least partially axially out of inductive heating relation 

